1. Field of the Invention
The present invention relates to a wired circuit board and a producing method thereof, and particularly to a wired circuit board used preferably as a suspension board with circuit and a producing method thereof.
2. Description of the Related Art
A wired circuit board used for electronic/electric equipment or the like is typically formed with a terminal portion to be connected to an external terminal.
In recent years, to respond to the increase in the density of electronic/electric equipment and the reduction in the size thereof, a flying lead having a terminal portion formed not only on one surface of a conductive pattern, but also on each of the both surfaces thereof has become prevalent. For example, it has been known that, in a suspension board with circuit used in a hard disk drive or the like, a terminal portion is formed as a flying lead.
For example, a suspension board with circuit has been known which includes a supporting board, a base layer formed on the supporting board, a conductive pattern formed as a predetermined wired circuit pattern on the base layer, and a cover layer covering the conductive pattern. In the suspension board with circuit, an opening is formed in the cover layer to expose the top surface of the conductive pattern, while an opening is formed in the supporting board and the base layer to expose the back surface of the conductive pattern, so that the conductive pattern the both surfaces of which are exposed is used as a flying lead (see, e.g., Japanese Unexamined Patent No. 2003-031915).
In such a suspension board with circuit, protruding portions are provided to protrude from the insulating layers to the surfaces of the flying lead and the flying lead is provided with a wider portion to inhibit the flying lead from being disconnected due to ultrasonic vibration when the flying lead is connected to an external terminal or the like.